1. Field of the Invention
The present invention pertains to a thermostat sub-base having a control circuit including a radio frequency signal receiver and a heat source for controlling a thermostat to setback the thermostat set temperature in response to transmission of radio frequency control signals to the receiver over the thermostat power line.
2. Background
The increased cost of energy has made it highly desirable to more efficiently control the heating and cooling of air conditioned spaces in homes, office buildings, hotels and various other installations. Remote control systems have been developed which are adapted to transmit radio frequency control signals from a central control station over power lines leading to various appliances such as heating and air conditioning units to remotely energize or deenergize the units using a receiver and a switch controller located at each appliance for selective control. Temperature responsive controllers or thermostats have also been developed with are time controlled to setback the controlled temperature in a conditioned spaced when the space is unoccupied or, for example, in a home or hotel when the occupants are sleeping. Temperature setback and other control modes have been provided for thermostats which are so called hard wired to a control station and by the use of radio frequency or so called wireless signal transmission as described above. An example of a remote control system for control of various appliances by transmission of radio frequenct signals over power line wiring is described in U.S. Pat. No. 4,217,646 to Caltagirone, et al. and assigned to the assignee of the present invention.
However, the installation of a complete remote control system is relatively complex and typically only feasible in new installations. Retrofitting of existing thermostat installations with hard wired remote control switching is also impractical in many installations. It is also, of course, quite expensive to replace existing thermostats with new ones equipped with radio frequency signal receivers. Accordingly, it has been considered particularly desirable to be able to retrofit existing heating and air conditioning installations by the addition of a device which will provide remote control of temperature setback without rewiring the existing control system and without requiring the installation of new thermostat controls. It is to this end that the present invention has been developed. The invention provides a unique thermostat mounting structure which is adapted to provide for temperature setback utilizing existing thermostat devices and also adapted to be remotely controlled by the transmission of radio frequency signals over the existing thermostat control circuit.